Backplane having strip transmission line ethernet bus

ABSTRACT

A data server having a plurality of hot replaceable processing unit modules. Each module includes a motherboard having plugged therein: a CPU; a main memory; an I/O adapter card, and an interconnect printed board, electrically connected to the motherboard. A backplane has a first connector adapted for coupling to a DC power supply. The interconnect printed circuit board has a DC to DC converter connected to a second connector adapted to mate with the first connector to enable the processing unit module to be hot plugged into, or removed from, the backplane. The backplane has formed thereon a strip transmission line adapted to provide an Ethernet bus for interconnecting a plurality of the modules. A cable management system for a cabinet used to house the module includes at least one vertically extending channel disposed in the cabinet and a fastener adapted to open and enable the a cable to be inserted into the channel and close to retain such cable within the channel. A chassis having a plurality of shelves for supporting electrical modules with a partitioning member adapted for removable insertion onto one of the shelves to accommodate modules with different widths. An I/O adapter card mounting plate, with captive hardware, adapted for securing an array of I/O adapted cards, and honey-combed I/O adapter card filler plate to a case. A method for booting operating system software into a main memory of a processing unit.

This is a Divisional patent application of U.S. patent application Ser.No. 08/885,381, filed Jun. 30, 1997, which is pending.

BACKGROUND OF THE INVENTION

This invention relates generally to data servers and more particularlyto data servers adapted to move data between a network and a datastorage system.

As is known in the art, data servers are used to move data between astorage system, such as between a Symmetrix Integrated Cached Disk Arraystorage system and a network.

The data server typically includes a set AC powered processing unitmodules each of which includes a central processing unit (CPU),input/output (I/O) adapter cards, and a main memory programmed to run avariety of software application programs for subscribers to the network.These applications include file access, video access and/or networkbackup. In one such data server, a set of five, AC powered, personalcomputers (PCs) are packaged inside a standard 19 inch cabinet. The fivePCs are connected together via a twisted pair cable to an Ethernet hub.A laptop PC is used as a control station for the other PCs. Akeyboard/monitor multiplexer (mux) was used to pass each PC's bootsequence with a single keyboard and monitor.

SUMMARY OF THE INVENTION

In accordance with one feature of the invention, a data server isprovided having a plurality of hot replaceable processing unit modules.Each one of the processing unit modules includes a CPU, main memory andI/O adapter card.

In a preferred embodiment of the invention, the data server includes abackplane having a first electrical connector adapted for coupling to aDC power supply. Each one of the processing unit modules is DC powered.The module includes a motherboard having plugged therein: the CPU; themain memory; and the I/O adapter card. The module includes aninterconnect printed board, electrically connected to the motherboard.The interconnect printed circuit board has mounted to it a secondelectrical connector and a DC to DC converter electrically connected tothe second electrical connector. The second electrical connector isadapted to mate with the first electrical connector to enable theprocessing unit module to be hot plugged into, or removed from, thebackplane.

In accordance with another feature of the invention, a data server isprovided having a cabinet with a plurality of slots, or compartmentstherein. Each one of the slots has a backplane disposed at the rearthereof. A plurality of hot replaceable, DC powered processing unitmodules is provided. Each one of the modules is adapted to be insertedin, or removed from, a corresponding one of the slots as such one of theprocessing unit modules is plugged into, or un-plugged from thebackplane.

In accordance with another feature of the invention a printed circuitboard is provided with a pair of overlying strip conductors forming astrip transmission line. The strip transmission line is configured withelectrical characteristics of a coaxial transmission line.

In a preferred embodiment of the invention, the AC impedance and DCresistance of the strip transmission line are selected to configure thestrip transmission line as an Ethernet coaxial transmission line.

In accordance with another feature of the invention, a printed circuitbackplane is provided having an electrical connector adapted to matewith, and electrically connect to, an electrical connector of adaughterboard. The backplane has a pair of overlying strip conductorsforming a strip transmission line. The strip transmission line isconfigured with electrical characteristics of a coaxial transmissionline. In a preferred embodiment of the invention, the AC impedance andDC resistance of the strip transmission line are selected to configurethe strip transmission line as an Ethernet coaxial transmission line.

In accordance with another feature of the invention, a backplane isprovided having a first electrical connector mounted thereto adapted tohave plugged therein a daughterboard. The daughterboard has a secondelectrical connector adapted to mate with, and electrically connect to,the first electrical connector. The backplane has a first stripconductor disposed on one a surface of a dielectric substrate thereofand a second strip conductor on an opposite surface of the dielectricsubstrate. The first and second strip conductors are in overlayingrelationship to provide a strip transmission line from a coaxialconnector mounted to the backplane to the first electrical connector.

In a preferred embodiment, the strip transmission line provides anEthernet bus on the backplane.

In accordance with another feature of the invention, a cable managementsystem is provided for a cabinet adapted to house electrical components.The cable management system includes at least one longitudinallyextending channel disposed in the cabinet. A fastener is providedadapted to open and enable the a cable to be inserted into the channeland close to retain such cable within the channel.

In a preferred embodiment, the channel includes a portion of a frame ofthe cabinet.

In accordance with still another feature of the invention, a chassis isprovided having a plurality of shelves for supporting electricalmodules. A partitioning member is provided having captive, manuallyoperable hardware adapted for removable insertion onto one of theshelves. The shelf has a pair of slots adapted to receive a pair ofmodules when the partitioning member is fastened to the shelf. Suchshelf has a single slot adapted to receive one module with width greaterthan the width of one of the pair of modules when the partitioningmember is removed from the shelf. The partitioning members of one of theshelves may be removed from, or inserted onto, the shelf withoutinterrupting operation of the modules on the other shelves.

In accordance with yet another feature of the invention, a powermanagement system is provided. The system includes a cabinet havingstored therein: a battery; a plurality of redundant, independentlyreplaceable battery chargers. One of the pair of battery chargers may bereplaced if defective without effecting the operation of the other oneof the battery chargers in charging the battery.

In accordance with still another feature of the invention, an I/Oadapter card mounting plate is provided for securing an array of I/Oadapter cards to a case. Each one of the I/O adapter cards has mountedthereto a mounting bracket. A motherboard is disposed in the case and isadapted to have plugged therein the array of I/O adapter cards. Themounting plate has captive fastening hardware and is adapted to beplaced over the mounting bracket as a single piece.

The captive hardware is adapted to enable manual fastening of themounting member to secure the mounting bracket between the mountingplate and the case after the array of I/O adapter cards has been pluggedinto the motherboard.

In accordance with yet another feature of the invention, an adapter cardfiller plate is provided. The filler plate has a plurality of holesformed therethrough to provide a honey-combed structure. If an I/Oadapter card is not needed, an adapted card filler plate is substitutedfor it. The filler plate is fastened to a mounting bracket by themounting plate. The honey-combed, adapted card filler plate improvesair-flow through the case.

In accordance with still another feature of the invention, a method isprovided for booting operating system software into a main memory of aprocessing unit module. The method includes the step of executing aprogram stored in the processing unit module to sequentially search aplurality of possible sources of the operating system software during aboot-up phase. When a possible source of the operating system softwareis detected, the CPU checks to determine whether such detected source isoperational and has a valid boot format. If the detected source isoperational and has a valid boot format, the CPU boots the detectedoperating system software source into the main memory. If the detectedsource is either non-operational or does not have a valid boot format,the CPU checks another one of the possible operating system softwaresources. If all sources are checked and none are operational nor have avalid boot format, the CPU repeats the aforementioned sequential searchof the possible operating system software sources.

With such a method, the processing unit module is able to successfullyboot-up when the operating system software is stored in a relativelylarge memory system which may take a substantially long time to beoperational compared to the relatively short boot-up time of theprocessing unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features of the invention, as well as the invention itself, willbecome more readily apparent from the following detailed descriptiontaken together with the accompanying drawings, in which:

FIG. 1 is a diagram of a data server according to the invention coupledbetween a memory system and a network;

FIG. 2 is a drawing of the data server of FIG. 1;

FIGS. 3A-3C are simplified, diagrammatical sketches of the data serverof FIG. 1, FIG. 3A showing the front door of a cabinet used to store thecomponents of the data server of FIG. 2, FIG. 3B showing the front ofthe cabinet when the front door of FIG. 3A is open; and FIG. 3C is arear view of the cabinet when a rear door thereof is open.

FIGS. 4A and 4B are perspective views of the data server of FIG. 2; FIG.4A being a rear perspective view of the data server with the rear dooropen; and FIG. 4B being a front perspective view of the data server withthe front door open; FIGS. 4C and 4D are front perspective and topdiagrammatic drawings of the data server of FIG. 2 with the cabinetthereof being shown in phantom; and FIG. 4E is a rear view of a set offour backplanes used by the server of FIG. 2;

FIGS. 5A-5H are drawings of a processing unit module used as either adata mover or control station in the data server of FIG. 2; an exemplaryone of the data movers and control stations being shown in FIGS. 5A-5G;FIGS. 5A, 5B, 5G showing an exemplary one of the data mover module; andFIGS. 5F and 5H show an exemplary one of the control station modules;FIGS. 5C and 5E are diagrammatical in nature and represent either a datamover or control station modules;

FIG. 5D shows a processing unit module case prior to being configured aseither a data mover or control station processing unit module;

FIG. 6 is a block diagram of a power management system, according to theinvention, used in the server of FIG. 2;

FIG. 7 is a diagrammatical sketch showing a Ethernet strip transmissionline, according to the invention, formed on a backplane and used tointerconnect modules plugged into the backplane and coaxial cables usedto interconnect a plurality of such backplanes;

FIG. 8 is a block diagram of the data server system of FIG. 1;

FIGS. 9A though 9C are drawings used to illustrate an I/O adapter cardmounting plate according to the invention; FIG. 9A is a sketch of anarray of such I/O adapter cards; FIG. 9B is an exploded cross-sectionaldiagrammatical sketch showing the arrangement between the mountingplate, an I/O adapted card and a mounting member provided on a frontbezel of a module; and FIG. 9C is an isometric, exploded drawing of theI/O adapter plate mounting member according to the invention;

FIGS. 9E-9G are drawings of an I/O adapter card filler plate accordingto the invention adapted for use in place of an I/O adapter card inFIGS. 9A-9D, FIG. 9E being a perspective view of the filler plate andFIGS. 9F and 9G showing the filler plate of FIG. 9E mounted to the frontbezel of a module;

FIGS. 10A-10F are drawing useful in understanding a the operation of alocking mechanism used by the modules; FIGS. 10A-10D showing the lockingmechanism in the locked position and FIGS. 10E and 10F showing thelocking mechanism in the unlocked position;

FIGS. 11A-11G are perspective views of a chassis used by the server ofFIG. 2 to store up to four processing unit modules shown in FIG. 5A;FIG. 11A showing the chassis with partitioning members; FIGS. 11B and11C being perspective views of front and rear partitioning members,respectively, adapted for use with the chassis of FIG. 11A; FIG. 11Dbeing a perspective, exploded view of the chassis with the partitioningmembers of FIGS. 11B and 11C; FIG. 11E is a sketch showing the chassisof FIG. 11A with the partitioning members of FIGS. 11A and 11B mountedtherein to provide such chassis with four slots to receive four modulesas shown in FIG. 11F; and FIG. 11G is a rear perspective view of thecabinet of FIG. 11A;

FIGS. 12A-12D are drawings useful in understanding "blind mating"between a module of FIG. 5B and its mating backplane of FIG. 4C;

FIGS. 13A and 13B are drawings showing strip conductor circuitrydisposed on a front and rear surface of a dielectric substrate used inthe backplane of FIG. 4C, such strip conductors overlaying each other toform a strip transmission line Ethernet bus of FIG. 7;

FIG. 14A is a perspective view of the cabinet shown in FIG. 2, such viewshowing a cable management system according to the invention; FIG. 14Bis an exploded view of a portion of the drawing in FIG. 11A such portionbeing inclosed by a circle labelled 14B--14B in FIG. 14A; and FIG. 14Cis a top view of the cable management system;

FIG. 15 is a diagram of the server of FIG. 2 connected to a test networkduring factory test; and

FIG. 16 is a flow diagram of a method, according to the invention, forbooting an operating system software into a main memory of each of theprocessing unit modules used in data movers and control stations of thedata server of FIG. 2 during either factory test, as in FIG. 15 orduring normal operation, as in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS GENERAL OVERVIEW

Referring now to FIG. 1, a data server 10 is shown coupled between astorage system 12 and a network 14. The storage system 12 is here aSymmetrix 3500 Integrated Cache Disk Array system manufactured and soldby EMC Corporation, Hopkington, Mass., assignee of the present patentapplication. The storage system 12 is coupled to the data server 10through a Fast Wide Differential (FWD) SCSI interconnect 16, as shown.

The data server 10 includes, in a single cabinet 18 shown in FIGS. 2,3A-3E, a plurality of, here up to sixteen hot replaceable processingunit modules 28. Up to fourteen of the processing unit modules 28 aredata movers 20, here labelled 20₁ -20₁₄ and up to two of the processingunit modules 28 are control stations 22 here labelled 22₁ -22₂.

The processing unit modules 28 are all interconnected through a localbus, here an Ethernet bus 24 (FIG. 1). (Hot replaceable means that acomponent can be removed and/or replaced without an interruption to thesystem's, here server's, operation.) It should also be noted that themodules 28 are configured so that no cables need to be physicallyremoved from the module 28 in order to remove it from the cabinet 18.

There are sixteen slots, or compartments (FIG. 3B) in the cabinet 18into which the processing unit modules 28 (i.e., data movers 20₁ -20₁₄or control stations 22₁, 22₂) can be slidably inserted or removed. Theslots are arranged in longitudinally, here vertically, extending pairs;the top seven pairs being configured to receive data movers 20₁ -20₁₄,and the bottom pair being configured to receive the control stations22₁, 22₂. One of the slots in the bottom pair can be configured as afifteenth data mover 20 or it may be configured as a redundant controlstation 22. The data movers and control stations 20₁ -20₁₄, 22₁ -22₂ areconnected to the storage system 12 through the SCSI interconnect 16, asnoted above, and to the network 14 though bi-directional busses 26, asshown in FIG. 1.

The control stations 22₁, 22₂ have different functions depending on thesoftware application that is running on the data server 10 for asubscriber to the network 14, for example. Each data mover 20₁ -20₁₄ orcontrol station 22₁, 22₂ is disposed within a sheet metal case toprovide an enclosure for the processing unit module 28, as shown inFIGS. 4A and 4B. An exemplary one of the data movers and control stationprocessing unit modules 28 is shown in FIGS. 5A-5G. It is noted thatFIGS. 5A, 5B, 5G show an exemplary one of the data mover 20 processingunit modules 28, here data mover 20₁ while FIGS. 5F and 5H show anexemplary one of the control station 22 processing unit modules 28, herecontrol station processing unit module 28. FIGS. 5C and 5E arediagrammatical in nature and represent either a data mover 20 or controlstation 22. FIG. 5D shows a processing unit module 28, here an emptycase, prior to being configured as either a data mover or controlstation. Each processing unit module 28 is DC powered, environmentallycontrolled processing unit module. The processing unit module 28includes a motherboard having plugged therein a CPU, main memory, andI/O adapter cards, to be described in detail hereinafter. Suffice it tosay here, however, is that the processing unit modules 28 are hotreplaceable into, or from, the server 10 via four backplanes 30₁ -30₄(FIG. 3C). More particularly, the processing unit modules 28 for datamovers 20₁ -20₄ are hot replaceable via backplane 30₁ ; the processingunit modules 28 for data movers 20₅ -20₈ are hot replaceable viabackplane 30₂ ; the processing unit modules 28 for data movers 20₉-20₁₀, are hot replaceable via backplane 30₃ ; and, the processing unitmodules 28 for data movers 20₁₁ -20₁₄ and for control stations 22₁, 22₂are hot replaceable via backplane 30₄.

Referring again also to FIG. 3B, the data server 10 also includes a CDROM drive 50, accessible when the front door 36 of cabinet 18 is opened,and a multiplexer board (MUX) 53.

Referring to FIGS. 3A-3C, the data server 10 includes a flat paneldisplay 32 and keyboard with trackball mounted on the front door 36 ofthe cabinet 18.

The data server 10 also includes a power management system 40, to bedescribed in more detail in connection with FIG. 6. Suffice it to say,here, however that the data server 10 includes an Emergency Power Off(EPO) box 42 (i.e., a circuit breaker, line filters, controller andswitches to enable switch over from primary AC main line 37a power feedto auxiliary AC main line power feed 37b), a plurality of power supplies(e.g., AC to DC converters) 38, one thereof being provided forredundancy. The AC to DC converters 38 are modular, redundant, andindependently hot replaceable via a connector plate, not shown, mountedto an L-shaped printed circuit board 44 (FIGS. 3C and 6). In order toprotect against power failure a battery back up (BBU) unit 46 isprovided. The battery back up unit (BBU) 46, which includes battery 47,is charged by a pair of redundant battery chargers 48a, 48b eachindependently hot replaceable via the connector plate, not shown,mounted to the L-shaped printed circuit board 44, for charging thebattery 47.

Also provided are a pair of power control boards (COMMBDs) 52. TheCOMMBDs 52 will be described in more detail below in connection withFIG. 6 and the power management system 46. Suffice it to say here,however, that the COMMBDs 54 are coupled to the server backplanes 30₁-30₄ though the L-shaped printed circuit board 44, as shown in FIG. 6.Each COMMBD 54 is adapted to sense a variety of conditions, including:which data movers 20₁ -20₁₄ are present in each data mover backplane 30₁-30₄ ; which backplanes 30₁ -30₄ are present; whether there are Ethernetbus 50 ohm terminator resistors 56, to be described in more detail inFIG. 7 in connection with the internal Ethernet bus 34, a portion ofwhich is formed as a strip transmission line 58 on the backplanes 30₁-30₄ ; how many battery chargers 48a, 48b there are and whether theircables are plugged in; whether the EPO 42 is present or absent; thenumber of power supplies 38 (i.e., one to six); mux board 53 present orabsent; and, CDROM 50 present or absent.

The L-shaped printed circuit board 44 is the wiring backbone of the dataserver 10. There are two facets to the L-shaped printed circuit board44: there are connections on the L-shaped printed circuit board itselfto enable its connection to the backplanes 30₁ -30₄ by a ribbon cables31; and, there is a connector plate, not shown, mounted to the L-shapedprinted circuit board 44 for plugging in the EPO box 42 and batterychargers 48a, 48b allowing for "quick-disconnect" of the batterieschargers 48a, 48b.

SERVER 10 SYSTEM BLOCK DIAGRAM

Referring now to FIG. 8, a system block diagram of the data server 10 isshown. As noted above, the processing unit modules 28 (i.e., data movers20₁ -20₁₄ and control stations 22₁, 22₂) communicate with each otherthrough an Ethernet bus 24, here a pair of redundant Ethernet busses24a, 24b, as shown, to the network 14 via an ATM, Ethernet or FDDIbi-directional buses 26 (FIG. 1), for example, and to storage system 12via the FWD SCSI, or Fibre channel interconnect 16 (FIG. 1).

It is noted that the control stations 22₁, 22₂ each includes a floppydisk 60 and optional hard drive 62. The control stations 22₁, 22₂ arealso here shown connected to the network 14 with ATM buses, however, itshould be understood that other buses may be used such as Ethernet orFDDI, for example. As noted above, here the control stations 22₁, 22₂are connected to the storage system 12 through SCSI channels 16, here apair of redundant SCSI channels. The control stations 22₁, 22₂ areadapted for coupling to modems, not shown, via communication, or COMMports 64, as indicated.

The control station 22₁, 22₂ motherboards 67, to be described inconnection with FIGS. 5C, 5E, are provided with keyboard, mouse, VGA andIDE interface cards 66 for enabling connection to a flat panel display32, keyboard 34, mouse and CDROM drive 50 via multiplexer 53, asindicated. Thus, the control stations 22₁, 22₂ have access theretothough the multiplexer 74. Therefore, the two control stations 22₁, 22₂share a common display 32, keyboard 34, mouse and CDROM 50. One of thesecontrol stations 22₁, 22₂ can act as a redundant control station so thatif one of the two control stations 22₁, 22₂ fails, the other one isstill operational.

Likewise, if one of the pair of Ethernets 24a, 24b (FIG. 6) fails, thedata server 10 can operate with the other one. If one of the storagechannels, here FWD SCSI channels 16a, 16b, fails, the other one stillenables communication with the storage system 14. As noted above, thereis redundancy in AC-DC converters 38 and battery chargers 48a, 48b.

The control stations 22₁, 22₂ are responsible for communicationsinterconnect between themselves and the data movers 20₁ -20₁₄, viaserver interconnect printed circuit boards 68 in each control station22₁, 22₂ and data mover 20₁ -20₁₄. The system interfaces (e.g.,environmental, internal Ethernet communications, modem, and network andstorage) are all available to the control stations 22₁ -22₂.

The particular functions of the control stations 22₁, 22₂ may varydepending upon the application in use, but generally include: managementof the individual data movers 20₁ -20₁₄, power management and cooling(i.e., environmental) management. The control stations 22₁, 22₂ include,in addition to the motherboard 67 (FIG. 5E) with six I/O adapter cardslots, a 3.5 inch high density floppy disk drive 60, as shown in FIG.5H.

The processing unit modules 28 are powered by AC-to-DC converters, i.e.power supplies) 38 which are fed by the dual line AC through the EPO box42 to the AC-to-DC converters 38. The output of the AC-to-DC convertersis here 48 volts DC and is fed to each of the DC to DC converters 70mounted to each of the server interconnect printed circuit boards 68(FIG. 5E) included within each one of the processing unit modules 28,described above. There is a battery backup unit (BBU) 46. There are tworedundant, hot replaceable, battery chargers 48a, 48b (FIG. 6) externalto the battery backup unit 46. AC power may be lost up to severalminutes, during which time the battery 47 in the BBU 46 will power theserver 10. Charge is maintained in the BBU 46 by one of the two,independently hot replaceable battery chargers 48a, 48b. It wasrecognized that what typically fails in a system having a backup battery47 (FIG. 6) is the battery charger. Thus, here, the battery chargers48a, 48b are external to the battery 47 and each of the chargers 48a,48b, one being redundant, is hot replaceable, as shown in FIGS. 4A, 4B,6. Thus, rather than embedding the chargers 48a, 48b in the BBU 46 andthereby having to replace an entire, relatively heavy, typically 50pounds BBU 47 in the event of a battery charger failure, here thetechnician merely hot un-plugs the failed one of the two batterychargers 48a, 48b and replaces it with an operational battery chargerwhile the server 10 continues to operate without interruption. When ACpower is present from either the main AC line 37a or the auxiliary ACline 37b, the AC-DC converters 38 provide power to the processing unitmodules 28 via a 48 volt bus system (i.e., a +48 volt bus and a groundbus) and one of the battery chargers 48a, 48b supplies a trickle chargeto the battery 47. It is noted that when there is AC power present, theoutput voltage of the AC/DC converters 48 is slightly above 48 volts toback bias diode 72a (FIG. 8) while diode 72b (one diode being includedin each converter 48) is forward biased. When there is a completefailure of AC power, power to the processing unit modules 28 is suppliedby the battery 47 via the 48 volt bus to the backplanes 30₁ -30₄. Theone of the two battery chargers 48a, 48b producing the highest potentialis selected as the one to charge the battery 47.

As noted above, the data server 10 has n plus one AC-to-DC converters 38(i.e., power supplies 38); here, n is five. Each processing unit module28 includes an interconnect printed board 68, electrically connected to(i.e., plugged into) the motherboard 67. The interconnect printedcircuit board 68 (i.e., a daughterboard for the backplane 30) hasmounted to it an electrical connector 93, to be described, and a DC toDC converter 70 electrically connected to the electrical connector 93.The electrical connector 93 of the interconnect printed circuit board 68is adapted to mate with, and electrically connects to, one of thebackplane 30₁ -30₄ electrical connectors 254a, 254b, 254c, or 254d (FIG.12B). DC power from the 48 volt bus system is connected to pins of thebackplane 30₁ -30₄ connectors 254a-254d. The DC to DC converter 70electrically connected to the electrical connectors 254a-254d thendistributes the 48 volts to other components of the processing unitmodule 28 and enables the processing unit module 28 to be hot pluggedinto, or removed from, the backplane 30₁ -30₄.

More particularly, each one of the processing unit modules 28 includes aserver interconnect printed circuit boards 68. As noted above, each oneof the boards 68 has mounted to it a DC-to-DC converter 70. The DC to DCconverter 70 creates the required DC voltages (i.e., here +3.3, +5volts, +12 volts, etc.) from a bulk 48 volt on the 48 volt bus that isdistributed throughout the cabinet 18. More particularly, the 48 voltsis then converted by the DC to DC converter 70 mounted to the serverinterconnect printed circuit board 68 to the voltages required bycomponents, i.e., fans, CPU, optional disk drive, etc. in the processingunit module 28. These required voltages may be, for example, 5 volts DC,12 or 3.3 volts DC. The server interconnect printed circuit boards 68each have mounted to them a pair of redundant Ethernet transceivers(XCVRs).

DATA MOVER/CONTROL STATION PROCESSING UNIT MODULE 28

As noted above, each data mover 20₁ -20₁₄ or control station 22₁, 22₂ isdisposed within a sheet metal case to provide a processing unit module28, an exemplary one being shown in FIGS. 5A-5H. Each case houses a DCpowered, environmentally controlled processing unit module 28. Theprocessing unit module 28 includes the motherboard 67 (FIG. 5E) disposedon the bottom of the processing unit module 28, the data serverinterconnect printed circuit board 68 mounted along one side of theprocessing unit module 28, and a pair of DC fans 76, 78 disposed on theback of the processing unit module 28.

Referring also to FIGS. 5B and 5C, the server interconnect printedcircuit board 68 has mounted to it the DC to DC converter 70 (FIG. 8), aDC margin and thermal control unit module, a pair of control busses, apair of Ethernet 10 Base2 busses, a parallel port interface and variousindicators 77 and switches 79 (FIGS. 5G and 5H) accessible from thefront panel of the processing unit module 28. The thermal control unitprocessing unit module 28 is used to control the fans 76, 78, and hencethe environment, of such processing unit module 28. The processing unitmodule 28 interconnect printed circuit board 68 (i.e., a daughterboard)plugs into the motherboard 67 (FIG. 5E). The DC fans 76, 78 have atachometer, not shown. and the server interconnect printed board 68 hasfan detection logic that determines if the fans 76, 78 are stillrotating properly. If a fan failure has occurred a fan₋₋ tach fault ispresented to the control stations 22 via the backplane 30₁ -30₄. Thecontrol stations 22 provide the mechanism in which to turn on/off thepower to an individual data mover/control station processing unit module28. Airflow through the data mover/control station processing unitmodule 28 is from front to back, as shown in FIG. 4B. The DC operatedfans 76, 78 pull air from slots in the front panel (FIG. 5B) of the datamover/control station processing unit module 28 and across themotherboard 67.

The motherboard 67 (FIG. 5E) has mounted to it a central processing unit(CPU) 80, here a Pentium processor, a cache memory, main memory 82a(FIG. 5C) (i.e., RAM SIMM modules adapted for insertion intoconventional SIMM slots 82), PCI bus slots 84, ISA bus slots 86. Theslots 84, 86 are adapted to receive plug-in standard I/O adapter cards,an exemplary array 85 being shown in FIG. 9A. (As will be described, thedata movers 20₁ -20₁₄ here have four PCI slots 84, 86 and four ISA slots(FIG. 5G) whereas the control stations 22₁, 22₂ have two PCI slots 84,four ISA slots 86, and a floppy disk drive 60 (FIG. 5H). The I/O adaptercards 85 may also include SCSI, ATM, Ethernet FDDI and ESCON cards, forexample. The motherboard also has mounted to it a flash memory, or ROMhaving stored therein the CPU 80 self-test program (and BIOS).

It is noted that the processing unit module 28 is configured to enableuse of market available processing unit module motherboards and I/Oadapter cards 85. Motherboards may range anywhere from five slotmachines to eight slot machines, for example. Here, the motherboard 67is an Intel PBP133ED70NC. As noted above, the data mover or controlstation processing unit module 28 has eight I/O adapter card slots 84,86 (i.e., 3 PCI, 4 ISA, and 1 mixed PCI/ISA). It also has 4 SIMM slots82 (FIG. 5E), uses a Triton Chipset, and is capable of 100 MB sustainedthroughput between processing unit 28 main memory 82a and the PCI bus.When the motherboard 67 is configured in a data mover, the two leftmostslots 84 house single channel SCSI cards, for example, that interface tothe storage devices in the data storage system 12 (FIG. 1). Moving tothe right, the next two slots 84 are for connection to the network 14(FIG. 1) (i.e., combinations of 100base T Ethernet, FDDI, ATM or otheradapters); the following two slots 86 to the right of the networkconnectors are here reserved for expansion, and the two rightmost slots86 are 10baseT Ethernet bus for communications between the data moverand the control stations 22₁, 22₂.

Because these motherboards 67 and adapter boards 85 are available inlarge quantities from a variety of sources, the data server 10 hasrelatively low cost and high performance.

Further, with respect to the use of standard I/O adapter cards, the dataserver 10 can rapidly deploy new network interfaces to the market. Afully loaded data server 10 has 60 slots 84, 86 that can be configuredwith network and/or storage I/O adapter cards 85. Each servermotherboard 67 has four available full length PCI slots and each controlstation has two available full length PCI slots. An exemplary dataserver 10 is configured with four-port Ethernet network adapters andsingle SCSI adapters would yield a system with one hundred and twentynetwork 12 connections and thirty data storage system 14 connections.

The server interconnect printed board 68 provides the status, controland communication interfaces for the server 10. In effect, the serverinterconnect printed circuit boards 68 serve as a bridge between themotherboard 67 and the server 10 via the backplanes 30₁ -30₄. The serverinterconnect printed board 68 performs the following functions: (1) Itprovides a point of load DC-to-DC conversion for the motherboard 67; (2)It contains a control bus that allows the control station processingunit module 28 to perform numerous environmental operations to the datamover processing unit modules 28; (3) It collects the environmentalstatus that is local to the data mover and/or control station processingunit module 28 and reports on exceptional conditions; (4) It contains anEnhanced Parallel Port (EPP) which allows the motherboard 67 to gatherVital Product Data (VPD) and other configuration information, enablestheir battery backup functions, solicits on exceptional systemconditions, signals the control station via the control bus, andaccesses other system interfaces; (5) It contains a Legacy Parallel Port(LGP) that interfaces the control station to the COMM board (COMMBD)which contains other information/control about the system'sconfiguration and environment; (6) It has the pair of the redundantEthernet XCVRs to provide the means in which the communications Ethernetbus 24 is routed to other server/control stations; and, (7) It providesthe physical path for modem access from the control station.

Referring to FIGS. 5B, 5C and 5E, a Teradyne High Density Metric (HDM)connector 93 is mounted to the rear of server interconnect printedcircuit board 68. The rear of the HDM connector 93 projects outward froma slot 94 provided in the rear panel 98 of the processing unit module 28(FIGS. 5D and 5F); FIG. 5F showing processing unit module 28 with theinterconnect printed circuit board 68 removed. The upper portion 95 ofconnector 93 is adapted to receive the 48 volts provided by the AC/DCconverters 38 (FIGS. 6 and 8) on the 48 volt bus system. The middle andlower portions 97, 99 of the connector 93 (FIG. 5B) are adapted toreceive signals via the backplanes 30₁ -30₄. Disposed between the middleand lower portions 97, 99 of connector 93 is a hole 101. The rear panel98 of the processing unit module 28 (FIG. 5B) is provided with a hole105, as shown, disposed below the connector 93. As will be describedbelow in connection with the server cabinet 18, this arrangement is usedin a three-step "blind mating" arrangement enabling hot replacement ofthe processing unit module 28 from a backplane 30₁ -30₄ into which theprocessing unit module 28 plugs.

Referring again to FIGS. 5G and 5H, the front panel bezels 110 of thedata mover 20₁ module 28 and control station 22₁ module 28 are shown,respectively. The front bezels 110 have a handle 111, as shown. On thefront bezels 110 of each are several switches 79 and indicators 77. Moreparticularly, a service switch used only for manufacture, power enableLED indicators to indicate that power is enabled within the data mover20₁ -20₁₄, or control station 22₁ -22₂ ; a fault LED to indicate afailure in the control station or data mover module 28, a push buttonreset switch to perform a hard reset to CPU 80 mounted on themotherboard, and status LEDs. (The reset switch is a mechanical switchwhich restarts the CPU 80 to initiate a boot of the operating systemsoftware into the main memory 82a. As will be described in connectionwith FIG. 16, a program is stored in the processing unit module 28 (aportion in the flash memory mounted to the motherboard 67, mentionedabove, and another portion on the Ethernet adapter cards plugged intothe motherboard 67) to automatically reset the CPU 80 until the CPU 80finds an operational and valid source for the operating systemsoftware.) Here, there are twelve small status LEDs 77 (FIGS. 5G, 5H) toprovide additional information about the internal state of the datamover and/or control station module. The front bezel 110 of the controlstation 22 module 28 shows the physical location of the I/O adapter cardslots 84, 86. As described above, slot numbers 3 and 4 are PCI slots andslots 5 through 8 are ISA slots. FIG. 5G shows the front bezel 110 ofthe data mover and the physical location of the I/O adapter card slots84, 86. As described above, slots 1 through 4 are PCI slots. Slotnumbers 5 through 8 are ISA slots. Also, the front bezel 110 is providedwith a pair of openings 113a, 113b (FIG. 7) to enable connection of thepair of redundant Ethernet I/O adapter cards via connectors 113c, 113d(FIG. 7) between the pair of Ethernet I/O adapter cards (EI/O) and acorresponding one of a pair of redundant Ethernet transceivers (XCVRs)mounted to the server interconnect printed circuit boards 68, as shown,and to be described in connection with, FIG. 7.

Thus, in summary, the data movers/control stations comprise of amotherboard 67, a server interconnect printed circuit board 68, I/Oadapter cards 85, DC powered fan 76, 78, and a mechanical enclosure, orcase for the processing unit module 28. The case has a latchingmechanism 222 to be described in connection with FIGS. 10A-10F. Thus,referring again briefly to FIGS. 5G and 5H, the modules 28 include ontheir front bezels 110 panel, a handle 111 and locking mechanism 22₂that is used, as described above, to insert or remove the module 28 fromthe cabinet 18. The I/O adapter card slots 1-8 for data movers 20₁ -20₁₄and slots 3-8 for control stations 22₁, 22₂ are visible from the frontbezels 110 of the data mover or control station module 28.

I/O ADAPTER CARD MOUNTING PLATE 312

An exemplary array of I/O adapter cards 85 is shown in FIG. 9A. It isnoted that the I/O cards 85 are off-the-shelf printed circuit boardshaving an L-shaped mounting bracket 301. Each one of the L-shapedmounting brackets 301 has a leg portion 304 fastened to a printedcircuit board, or card 302 and a foot portion 306 with a U-shapedopening 308 passing through the foot portion 306 normally used toreceive a screw, not shown, used to securing the bracket 301 to amounting member 310 of the case (i.e., module 28 enclosure), forexample. The L-shaped mounting bracket 301 is, noted above, affixed to aprinted circuit card 302. The printed circuit card 302 is adapted tohave its bottom edge 303 plug into one of the slot 84, 86 (FIG. 5E) inthe motherboard 67. After the printed circuit card 302 is plugged intothe motherboard 67, rather then securing the L-shaped mounting bracket301 to the front panel 110 mounting member 310 with individual screws, amounting plate 312 having a plurality of captive screws 314 (FIG. 9C) isused.

More particularly, and referring also to FIGS. 5B, 5F and 9B, themounting plate 312 has press fit into a plurality of holes 316 (FIG. 9C)formed therein a corresponding plurality of screw fixtures 320, heremanufactured by Penn Engineering and Manufacturing Company, Danboro, Pa.18916, and a plurality of press fit pins 317 having tips 317a whichproject from the bottom of the plate 312 as a single unit to engage theU-shaped openings 308 in place of individual screws. The screw fixtures320 have an outer collar which is press-fit into the holes 316 in themounting plate 312 to thereby secure the screw fixtures 320 to themounting plate 312 as a single unit. The screws 314 are rotatablymounted within the screw fixtures 320. The distal ends 320 of the screws314, and, as described above, the tips 317a of pins 317, projectoutwardly from the bottom of the mounting plate 312. After one, or more,of the printed circuit boards 85 are plugged into the motherboard 67,the bottom of the mounting plate 312 is set over the horizontal footportion 306 of the L-shaped mounting brackets 301, as shown in FIG. 9B.The technician, using his/her thumb and forefinger about the outerperiphery of the screws 314, turns the screws 314 within the fixture 320clockwise to screw the screws 314 into the corresponding, tapped andthreaded holes 340 provided in the front panel 110 mounting member 310thereby mounting the entire mounting plate 312 to the front panel 110mounting member 310. Thus, the mounting plate 312, when secured to thefront panel mounting member 310, fastens the L-shaped brackets 304 tosuch front panel mounting member 310. Conversely, to remove one or moreI/O adapter cards 85, the technician turns the screws 314counter-clockwise until the mounting plate 312 is released from thefront panel mounting member 310. The technician then lifts and removesthe mounting plate 312. Once the mounting plate 312 is removed, thetechnician unplugs the desired I/O adapter card or cards 85. As notedabove, the screws are captive to the mounting plate 312 (i.e, the screws314 in their fixtures 320 are captive hardware to the mounting plate312). Further, the mounting plate 312 is a relatively large piece.Therefore, instead of having to contend with six or eight individualscrews, which are relatively small, difficult to handle individually,and subject to being dropped and difficult to retrieve, the single,relatively large mounting plate with captive hardware greatlyfacilitates the insertion and/or removal of the I/O adapter cards 85.Still further, a screw driver is not required.

I/O ADAPTER CARD FILLER PLATE

Referring now to FIGS. 9E-9F, an adapter card 85 filler plate 350 isshown. The filler plate 350 has an L-shaped mounting bracket 301' with afoot portion 306. The foot portion 306 has an U-shaped opening 308similar to that for the I/O adapter card 302 mounting brackets 301,described above. Here, however, the leg portion 351 has a plurality ofholes 352 formed therethrough to provide a honey-combed structure. Ifone of the I/O adapter cards 302 is not needed, one of the adapted cardfiller plates 350 is substituted for it, as shown in FIGS. 9F and 9G,where the fifth and sixth from the left adapter card filler plates 350are used in the module 28 to replace a pair of unused I/O adapter cards302. The filler plates 350 are fastened to the case of the module withthe mounting plate 312 (FIG. 9C). Thus, in this example, the tips 317aof pins 317 engage the U-shaped openings 308. This honey-combed, adaptedcard filler plate 350 improves air-flow through the front panel andacross the motherboard 67. It is noted that the distal end 353 isadapted to slip into slot S (FIG. 5D) provided in bottom panel of thecase of module 28.

SERVER 10 BACKPLANES 30₁ -30₂ WITH PRINTED CIRCUIT ETHERNET BUS

Referring again to FIGS. 3C-3E, the relationship between the serverbackplanes 30₁ -30₄ and the data movers 20₁ -20₁₄ processing unitmodules 28 and control stations 22₁ -22₂ processing unit modules 28, isshown. Thus, four backplanes 30₁ -30₄ connect up to fourteen streamservers 20₁ -20₁₄ and two control stations 22₁ -22₂. More particularly,fastened within in the cabinet 18 (FIG. 1) is a set of four sheet metalchassis 200, an exemplary one thereof being shown in FIG. 11A. Disposedbetween upper and lower panels 202, 204 is an intermediate shelf 206fastened to opposing side panels 210. Partitioning members 212a, 212b(FIG. 8B), are adapted for fastening with captive hardware screws 214,to threaded holes 207 provided in the front and rear center of the lowerpanel 204 (i.e., which serves as a bottom shelf) and the front and rearcenter of the shelf 206 (which serves as a middle shelf) to divide thelower panel 204 and/or the shelf 206 into right and left slots orcompartments 213a, 213b each compartment being adapted to receive amodule 28, as shown in FIG. 11F. Thus, when the partitioning members212a, 212b are fastened to lower panel 204 and the shelf 206, thechassis 200 is adapted to receive four modules 28, as described above,as shown in FIG. 11F. If, however, the width of a module 28 case isincreased in the future, the partitioning members 212a, 212b may beremoved allowing insertion of a larger module 28 case. The single module28 case would have its server interconnect printed circuit boardconnector 93 (FIG. 5B) on the left side of its case so that when thesingle module 28 case is slide onto the shelf the connector 93 will beable to be plugged into (i.e., mate with) the backplane 30₁ -30₄. It isnoted that a screw 253 (FIG. 11G) is adapted to pass through holes 253ain the backplane (FIGS. 12B, 13A and 13B) and be threaded into a hole253d in the rear wall 253c of partitioning member 212b.

More particularly, and referring also to FIG. 11G, the back panel 240 ofthe chassis 200 four slots 241a, 241b to enable the connectors 93 ofeach of the four modules 28 to project therefrom. If a single module 28is used on any one of the two shelves 204, 206, the connector 93 of suchmodule 28 will project from the appropriate one of the slots 241a.

The front of the side panels 210 are provided with slots 218, as shownin FIGS. 11A, 11D. As will be described, such slots 218 are adapted toengage the locking mechanism 222 (FIGS. 5G and 5H) on the module 28 tolock/unlock the module 28 in the cabinet 18.

As mentioned above, the chassis 220 has a rear panel 240 fasten to it,here welded, as shown in FIG. 11G. The rear panel 240 is provided withnine posts 242 (FIG. 11E) to receive corresponding nine holes 248passing though a corresponding one of the four backplanes 30₁ -30₄, anexemplary one being shown in FIG. 12A and 12B, the chassis 200 not beingshown for clarity. Further, the rear panel 240 carries captive screws243 which are adapted to pass through holes 253a in the backplane (FIG.13A, 13B) into a threaded rear wall 235c (FIG. 11C) in partitioningmember 212b (FIG. 11C).

The backplanes 30₁ -30₄ are identical in construction, an exemplary onethereof, here backplane 30₁ being shown in FIGS. 12A and 12B. Thebackplane 30₁ is a multi-level printed circuit board. The front of thebackplane 30₁ is shown in FIG. 12A to include four oval apertures250a-250d (FIG. 11A) adapted to align with the four oval openings252a-252d provided in the chassis 200 rear panel 240 (FIG. 11E). FourTeradyne HDM connectors 254a-254d (FIGS. 12A, 12B) are fastened to thebackplane 30₁, as shown; one to the right of a corresponding one of thefour apertures 250a-250d in FIG. 12B looking from the front of thecabinet 18. Each Teradyne HDM connector 254a-254d includes a forwardprojecting alignment pin 260, as shown for exemplary connector 254a inFIGS. 12C and 12D. Each backplane 30₁ -30₄ has fastened to it fourlonger alignment pins 261, as shown more clearly in FIGS. 12C and 12D.

As described above in connection with FIG. 5B, a Teradyne High DensityMetric (HDM) connector 93 is mounted to the rear server interconnectprinted circuit board 68 (FIG. 12D). More particularly, the serverinterconnect printed circuit board 68 is loosely mounted to the case 28so that it may move slightly upward if needed in mating connector 93with connector 254a. The rear of the HDM connector 33 projects outwardfrom a slot 94 provided in the rear of the module 28 (FIG. 5F) and inthe rear panel 242 of chassis 200 (FIG. 11E); FIG. 5F showing module 28with the interconnect printed circuit board 68 removed. The upperportion 95 of connector 93 is adapted to receive the 48 volts providedby the AC/DC supplies 38 (FIG. 6). The mid and lower portions 97, 94 ofthe connector 93 are adapted to receive signals. Disposed between themid and lower portions 97, 94 of connector 93 is a hole 41, as describedabove in connection with FIG. 5B. The rear panel 98 of the module 28(FIG. 5B) is provided with a hole 105, as shown, disposed below theconnector 93. The HDM connectors 93 of the data movers 20₁ -20₄ pluginto backplane 30₁ ; the HDM connectors 93 of data movers 20₅ -20₈ pluginto backplane 30₂ ; the HDM connectors 93 of data movers 20₉ -20₁₂ pluginto backplane 30₃ ; and the HDM connectors 93 of data movers 20₁₃, 20₁₄and of control stations 22₁, 22₂ plug into backplanes 30₄. The controlstations 22₁, 22₂ modules 28 as well as the data movers 20₁ -20₁₄modules 28 are hot replaceable directly (i.e., without any cablesbetween the module 28 and the backplane 30₁ -30₄ and without anyinterruption to the operation and data processing of the server 10).

In operation, the plugging of a module 28 into the backplane 30₁, forexample, is a three-step process. First, as the module 28 is slidbackwards toward the backplane 30₁, the point at the end of pin 261engages the hole 105 (FIG. 12A) in the module 28 thereby guiding (i.e.,aligning) the module 28 onto the shaft of the pin 261. Next, during thesecond step, as the chassis 28 is further urged rearward, the tip ofshorter pin 260 of HDM connector 254a engages the hole 101 in HDMconnector 93 thereby guiding the connector 93 onto the shaft of the pin260. As noted above, the server interconnect printed circuit board 68 isloosely mounted to the module 28 so that it may move slightly in themodule 28 as hole 101 and pin 260 engage each other. Finally, during thethird step, the plastic housings 257, 259 of the HDM connectors 93, 254aengage each other. This procedure enables "blind-mating" between themodule 28 (i.e., the sheet metal case of the module 28) and thebackplane 30₁ thereby enabling the module 28 to be hot plugged into, orremoved from the backplane 30₁, and hence into the data server 10 (FIG.1). It is noted that the module 28 is plugged into DC provided by thepower supplies 38 (FIG. 6), as distinguished from AC. That is, theprocessing unit module 28 has its own CPU 50, I/O adapter cards 85, mainmemory 82a and the DC/DC converter 70, is being hot plugged into, orremoved from a here 48 volt DC source; i.e., a 48 volt battery backed DCsupply 38.

Once the HDM connectors 93, 254a are plugged into each other, the module28 is locked into the cabinet 18. More particularly, as described above,the bottom of each module 28 has pivotally mounted to the front, lowerleft corner thereof a locking mechanism 222, as shown more clearly inFIGS. 5D and 10A-10F.

Here, the locking mechanism 222 is an arm 223 pivotally mounted at point224 (FIG. 10C) to the bottom of the module 28. It is noted that the leftside 226 of the locking mechanism arm 223 projects beyond the side 228of module 28, as shown when the right side 229 of the arm 223 ismanually urged rearward against the chassis 28; i.e., in the positionshown in FIGS. 10A-10C.

In order to insert the module 28 into the chassis 200, the technicianrotates the right side 229 of the arm 223 (i.e., the handle) forward,i.e., in the direction of arrow 231 (FIG. 10C), so that the left side226 of the arm 223 rotates rearward into a slot 230 provided in the leftside 226 of the module 28, as shown in FIGS. 10D-10F. In such position,the left side 226 of arm 223 no longer projects beyond the left side 228of the module 28 (FIG. 10F), but rather swings rearward and becomesrecessed in the slot 230 provided in the left side 226 of the module 28.In this position, the module 28 is slid onto the lower panel, or shelf,as the case may be, of the chassis 200 (FIG. 11D). When fully inserted,the technician urges the right side 229 of the arm 223 forward causingthe left side 226 of the arm 223 to pivot rearward (i.e., in the reversedirection of arrow 23) into the slot 218 (FIGS. 11C, 11D) provided inthe side 206 of the chassis thereby locking the module 220 in thechassis, i.e., preventing its removal unless the technician decides toremove the module 28 by again urging the right side 229 of the arm 223forward, as described above. It is noted that screw 225 (FIG. 10A) inarm 223 screws into hole 225a (FIG. 10D).

BACKPLANE HAVING STRIP TRANSMISSION LINE ETHERNET

The backplanes 30₁ -30₄ are multi-layer printed circuit boards.Patterned into the front and back surfaces of one of the dielectriclayers (referred to collectively herein as a dielectric substrate) ofthe printed circuit boards of the backplane 30₁ -30₄ are strip conductorcircuitry 262F, 262B, as shown in FIGS. 12A and 12B, respectively.Patterned into the front and back surfaces of another one of the printedcircuit board layer of the backplane 30₁ -30₄ are strip conductorcircuitry, not shown for a redundant Ethernet bus. The two layers arebonded together with suitable dielectric insulation to preventelectrical short circuits developing between the redundant Ethernetbusses 24. Considering one of the two Ethernet buses, here bus 24a, andrecognizing that the second bus 24b (FIG. 8) is substantially identicalto the first Ethernet bus 24a, the strip conductor circuitry 262F, 282Bmeanders, as shown, from a first Ethernet connector 270a, serially to apair of pins 274, 276 of each of the Teradyne connectors 254a-254d to asecond Ethernet connector 270b thereby providing the local Ethernet bus24a (FIG. 1) interconnecting the four modules 28 plugged into thebackplane 30₁. (It is noted that Ethernet connectors 270'a, 270'b areused for the redundant bus 24b, not shown).

Here, four Ethernet connectors 270a, 270b, 270'a-270'd, are here BNC10Base2 Ethernet connectors, mounted adjacent to a corresponding one ofthe apertures 250a-250d. Each Ethernet connector 270a-270b is a coaxialconnector having a center conductor 280 (FIG. 12A) and an outerconductor 282 (FIG. 11B). The center conductors 280 of the four Ethernetcoaxial connectors 270a, 270b are connected to strip conductor circuitry262F while the outer conductor 282 is connected to strip conductorcircuitry 262R. It is noted that the strip conductors 262F, 262R overlayone another as they pass from the first Ethernet connector 270a to thesecond Ethernet connector 270b. Further, the width of the return stripconductor 262R is wider that the width of the signal strip conductor262F thereby providing a strip transmission line. In order to emulate acoaxial transmission line, the AC impedance and DC resistance of theoverlaying strip conductor (i.e., the strip transmission line) aredesigned to have the substantially the same AC impedance and DCresistance of an Ethernet coaxial transmission line. More particularly,the AC impedance and DC resistance of the overlaying strip conductor(i.e., the strip transmission line) is designed to provide an ACimpedance, Z, of 50 ohms and a DC resistance, R, of 1.37 milli-ohms perinch. The following equations may be used: ##EQU1##

    R=ρ(L/A)Ω/inch

where:

e_(r) is the permissivity of the dielectric layer

w is the width of the signal strip conductor 262F

h is the thickness of the dielectric layer

t is the thickness of the signal conductor 262F

ρ is the resistivity of the signal or return conductor 262F, 262R

L is the length of the signal conductor 262F and

A is the area of the signal conductor 262F

By altering the geometry of the height (h), width (w), thickness (t),length (L) and area (A) the values of Z=50 ohms and R=1.37 milli-ohmsper inch are obtained. It should be noted that the return conductor 262Rserves as an radio frequency ground plane for the signal conductor 262Fand therefore should be wider that the signal conductor 262F. That is,the signal on the Ethernet bus 24a, 24b has a frequency of 10 MHz. Thus,the overlaying signal conductor 262F and return conductor 262F (with theintermediate dielectric printed circuit board layer) provide a striptransmission line for the Ethernet 10 MHz signal. Thus, the returnconductor 262R effectively serves an a non-DC ground, RF ground planefor the strip transmission line and is here 5 times greater in widththan the width, w, of the signal conductor.

To put it another way, the Ethernet busses 24a, 24b on the backplane 30₁are formed as strip transmission lines. That is, the backplane printedcircuit board is provided with a pair of overlying strip conductorsforming a strip transmission line. The strip transmission line isconfigured to have electrical characteristics of a coaxial transmissionline. More particularly, the AC impedance and DC resistance of the striptransmission line are selected to configure the strip transmission lineas an Ethernet coaxial transmission line.

Referring now to FIG. 7, the interconnection among the modules 28 viathe Ethernet buses 24a is shown. It is noted that while there are a pairof Ethernet busses 24a, 24b provided for redundancy, only one of thepair of busses, here bus 24a is shown in detail. Thus, there are fourmodules 28 shown for each one of the four chassis 200. Each module 28includes a pair of Ethernet I/O adapter card (EI/O) which is can beplugged into the motherboard 67 and which is in one of the slots 84, 86,as described above in connection with FIG. 5E. Each module 28 alsoincludes a server interconnect printed circuit board 68, as describedabove. The server interconnect printed circuit board 68 have a pair ofredundant Ethernet transceivers (XCVRs) mounted to it and has a TeradyneHDM connector 93 adapted for plugging into a mating Teradyne HDMconnector 254a-254d mounted to the backplane 30₁ -30₄.

The strip conductors 262F, 262R are connected to pins 272, 274 of theHDM connectors 254a-254d, as shown and as described above in connectionwith FIGS. 12A, 12B. The pins 272, 274 electrically connect to thecorresponding mating pin of the Teradyne connector 93 mounted to theserver interconnect printed circuit board 68. In this way, the modules28 are internally interconnected through the Ethernet bus 24a (or theredundant Ethernet bus 24b). That is, the strip transmission line passesfrom one processing unit module 28 to another module 28 in adaisy-chain, or serial manner connecting the four modules 28 pluggedinto each one of the backplanes 30₁ -30₄. The distance between each pairof directly connected Ethernet XCVRs must be greater than 20 inchestherefore, the strip transmission line meanders about the backplane asshown in FIGS. 12A, 12B.

It is noted that one of the coaxial connectors, here connector 270a ofbackplane 30₁ is terminated in a matching impedance, here a 50 ohmresistor 290. The other one of the coaxial connectors 270b of backplane30₁ is coupled to the coaxial connector 270a of the next backplane 30₂by a coaxial connector 292 and coaxial jumper cable, as indicated. It isto be noted that this coaxial connector 270b is not terminated in amatched 50 resistor. The process repeats until the last coaxialconnector 270b of backplane 30₄ is terminated in a matched impedance,here 50 ohm resistor, as shown, thereby serially connecting the 14 dataservers 20₁ -20₁₄ and two control stations 22₁, 22₂, as shown.

CABLE MANAGEMENT SYSTEM

"Front-end" (i.e. network 14, FIG. 1) and "back-end" (i.e., storagesystem 12) cables attached to the I/O adapter cards in slots 1-8 or 3-8,as the case may be, via the front of the data mover or control stationmodule enclosure 28. The cabling is achieved through a cable managementsystem. More particularly, cabling is achieved through front, sidepositioned cable channels 300, shown in FIG. 3B and to be described inconnection with FIGS. 14A-14C. The frame of the cabinet 18, shown inFIG. 14A, has provided in the left and right front regions thereof cablechannels 300. Each channel 300 includes one of four vertical edge struts30₂ at each of the four corners of the cabinet 18, as shown, and anadditional vertically extending strut 304. Connected to bridge theadditional struts 304 and the corner strut 302 are vertically spacedstraps 308, as shown. Each of the straps 308 has mating Velcrofasteners, not shown, at ends thereof. The rear portion of each strap308 is looped through slots formed in the channel 300 to secure thestrap 308 to the channel. When un-fastened, the cables, such as cables310, are manually held against the rear wall 312 of the channel 300 andthen the cables 310 are secured in the channel 300 by manually fasteningthe ends of the straps 308 together, as shown. Such arrangement providesstructure for neatly routing the cables 310 through the cabinet 18 atonly the added cost of the fasteners since the frame is required anyway.

POWER MANAGEMENT SYSTEM 40 WITH REDUNDANT, EXTERNAL, HOT 20 REPLACEABLEBATTERY CHARGERS

The power management system 40 is shown schematically in FIG. 6. Thesystem includes dual (i.e., redundant) AC power lines 37a, 37b feedingthe Emergency Power Off (EPO) box 37. The EPO 37 is electricallyconnected to the L-shaped printed circuit board connector 44. TheL-shaped printed circuit board 44 is electrically connected to thebackplanes 30₁ -30₄. Also electrically connected to the L-shaped printedcircuit board 44 are the pair of redundant, independently, hotreplaceable battery chargers 48a, 48b and six AC/DC converters 38. TheAC/DC converters 38 are fed AC power from the AC lines 37a, 37b throughthe EPO 42. The L-shaped printed circuit board 44 distributes DC to thepair of battery chargers 48a, 48b and DC, here 48 volts to the module 28(i.e., the server interconnect printed circuit boards 68), via thebackplanes 30₁ -30₄, as discussed above.

It is noted that while provision has been made to provide a Faraday cagethat houses six AC-to-DC converters 38 to thereby provide a 5 plus 1redundant power supply configuration.

The system can still operate in the event of a failure of one of theAC-DC converters 38. The total number of AC-to-DC converters with theserver 10 is six. Here, in FIG. 6 only four are shown; two are used forexpansion purposes and four are used for a fully configured system. Aminimum redundant configuration would be 1+1 AC-to-DC converters 38 anda maximum redundant configuration would be 3+1 AC-to-DC converters 38.The control stations 20 can detect the presence of all of the systemcomponents (e.g., processing unit modules 28, Ac-Dc converters 38,COMMBDs, etc.) and can algorithmically determine if there are enoughAC-DC converters 38 to power the server 10 before power is actuallyapplied to any of the other system modules 28.

A mechanical enclosure provides a Faraday cage for EMI emissions. EmptyI/O adapter card slots require small filler panels to prevent theleakage EMI. The mechanical case of the module 28 also provides ESDprotection to the internal printed circuit boards, SIMMs and disk drive(i.e., the control stations 22 have internal floppy and hard diskdrives). Each COMMBD 54, as noted above, is adapted to sense a varietyof conditions, including: which data movers are present in each datamover backplane; which backplanes are present; whether there areterminators on the backplane; how many battery chargers there are andwhether the cables are plugged in; EPO presence or absence; the numberof power supplies (i.e., one to six); mux board 53 presence or absence;CDROM presence or absence. The L-shaped printed circuit board 44 is, asnoted above, the wiring backbone of the system. There are two facets tothe L-shaped printed circuit board 44, as noted above: there areconnections on the L-shaped printed circuit board 44 itself; and, thereis a connector plate, not shown, behind the L-shaped printed circuitboard 44 for plugging in the EPO box 42 and chargers 38 allowing for"quick-disconnect" of the batteries 47 and chargers 48a, 48b. Theconnector plate has mating connectors that mate to the EPO 42 andchargers 38. There are also ribbon cables 31, as noted above, that comeout of the L-shaped printed circuit board 44 to electrically connect tothe backplanes 30₁ -30₄. Logically, then, the L-shaped printed circuitboard 44 connects to the EPO box 37 and the chargers 48a, 48b, but itdoes so through a series of cables having other ends fixed to themodules 28 (and routed through the channels 300) so that the modules 28can be removed.

OPERATING SYSTEM SOFTWARE BOOT PROGRAM EXECUTION METHOD

Referring now to FIG. 15, the server 10 of FIG. 2 is shown connected toa test network 100 via the Ethernet during factory test. Referring alsoto FIG. 16, a flow diagram of a method for booting an operating systemsoftware into the main memory 82a of each of the processing unit modules28 used in data movers 22 and control stations 24 of the data server 10of FIG. 2 during either factory test, as in FIG. 15 or during normaloperation, as in FIG. 1. It is noted that the integrated cached diskarray storage system 12 (FIG. 1) includes valid (e.g., valid format)operating system software, here DOS, which could be booted into the mainmemory 82a of a processing unit module 28 of the server 10. However,during normal operation (i.e., after delivery of the system to acustomer), if there has been a power failure, the time to the have thestorage system 12 operating system software available (i.e., valid) foruse by the processing unit module 28 after power is restored is muchgreater than the time the processing unit module 28 CPU 80 is ready toboot such operating system software into its main memory 82a. Thus, inorder to prevent the CPU 80 from getting locked into a non-bootablecondition because of the unavailability of the storage system 12operating system software, the method shown in FIG. 16 is used tosequentially restart the CPU 80 in its search for operational and validoperating system software.

In a factory environment, the server 10 may be tested without beingconnected to either the storage system 12 (FIG. 1) or the network 14(another possible source of an operational and valid operating systemsoftware), as shown in FIG. 15. There, the server 10 processing unitmodules 28 are booted with an operating system software stored in thetest network 100.

The method may be summarized as follows: A program stored is stored ineach one of the processing unit modules 28. The program is executed inparallel in each of the processing unit modules 28. More particularly, aread only memory on the motherboard 67 of each module 28, here a flashmemory stores the CPU 80 self-test portion of the program and theremaining portion is stored on the Ethernet I/O adapter card in theprocessing unit module 28. The program is executed to sequentiallysearch a plurality of possible sources of the operating system softwareduring a boot-up phase. The possible sources of the operating systemsoftware are: floppy drive, local hard drive (i.e., a hard drive of theprocessing unit module 28), CD ROM drive, a drive on the network 14(FIG. 1), a hard drive of the storage system 12 (FIG. 1), a tape drive,for example. When a possible source of the operating system software isdetected, the CPU 80 checks to determine whether such detected source isoperational and has a valid boot format. If the detected source isoperational and has a valid boot format, the CPU 80 boots the detectedoperating system software source into the main memory 82a. If thedetected source is either non-operational or does not have a valid bootformat (i.e., the source is operational but the CPU 80 reports"non-system disk error", for example), the CPU 80 checks the another oneof the possible operating system software sources. If all sources arechecked and none are either operational nor have a valid boot format,the CPU 80 repeats the aforementioned sequentially search of thepossible operating system software sources.

Referring to FIG. 16, the power to the CPU 80 in the processing unitmodule 28 is turned on (Step 400). The CPU 80 then starts its self-testby executing a program stored in the flash memory ROM in the processingunit module 28 to search for an operational, valid software operatingsystem software Step 401). Here, in this example, CPU 80, in response tothe executable program stored in the ROM of the processing unit module28, sequentially searches a plurality of possible sources of theoperating system software during a boot-up phase. More particularly,here the CPU 80 in this example, first searches the floppy drive for anoperational and valid operating system software, for example DOSoperating system software (Step 402). If, in Step 403, the CPU 80detects that the floppy drive has an operational and valid operatingsystem software, the CPU 80 boots such operating system software intothe main memory 82a (Step 404); if either an operational system is notdetected by the CPU 80 on the floppy or is found by the CPU 80 not to bea valid operating system software, the CPU 80 searches another one ofthe possible sources, here the local hard drive (Step 405). If, in Step406, the CPU 80 detects that the local hard drive has an operational andvalid operating system software (for example, the local hard drive hasoperational and valid operating system software, the CPU 80 boots suchoperating system software into the main memory 82a (Step 407); if eitheran operational system is not detected by the CPU 80 on the local harddrive or if detected is found not by the CPU 80 to be a valid operatingsystem software, the CPU 80 searches another one of the possiblesources, here the storage system 12 Step 408). If, in Step 409, the CPU80 detects that the storage system 12 has an operational and validoperating system software, the CPU 80 boots such operating systemsoftware into the main memory 82a (Step 410); if either an operationalsystem is not detected by the CPU 80 on the storage system 12 or ifdetected is found not by the CPU 80 to be a valid operating systemsoftware, the CPU 80 searches another one of the possible sources, herethe test network 100 (FIG. 15) (Step 409). If, in Step 411, the testnetwork 100 is used, as in a factory test, the system will boot;however, if the test network 100 is not used, as when the server 12 isat a customer, the program will reset the CPU (Step 414) and returns toStep 401 to again sequentially search for an operational and validoperating system software.

Other embodiments of the invention are within the spirit and scope ofthe appended claims. For example, the redundant, independentlyreplaceable battery chargers may be used in the memory system 12 tocharge a battery in such system 12.

What is claimed is:
 1. A data server, comprising:a cabinet having aplurality of slots therein, a backplane section disposed at a rear ofthe slots, such backplane section having mounted thereto a correspondingplurality of first multi-pin electrical connectors; a plurality of hotreplaceable, DC powered, processing unit modules, each one having aprinted circuit board, each printed circuit board having a secondmulti-pin electrical connector adapted be plugged into, or un-pluggedfrom a corresponding one of the first multi-pin electrical connectors ofthe backplane; and wherein such backplane comprises:a coaxial connectorhaving a center conductor and an outer conductor; a first stripconductor disposed on one surface of a dielectric substrate of thebackplane, such strip connector being electrically connected to thecenter conductor of the coaxial connector and to a first pin of thefirst multi-pin electrical connector; a second strip conductor disposedon an opposite surface of the dielectric substrate of the backplane,such second strip connector being electrically connected to the outerconductor of the coaxial connector and to second pin of the firstmulti-pin electrical connector, such first and second pins of the firstmulti-pin electrical connector being electrical connected to a pair ofpins of the second multi-pin electrical connector when the module isplugged into the backplane; the first and second strip conductors beingin an overlaying relationship to form a transmission line passing fromthe coaxial conductor to the electrical connector.
 2. The data serverrecited in claim 1 wherein the transmission line electricallyinterconnects the plurality of modules.
 3. The data saver recited inclaim 2 wherein the coaxial connector and one of the strip conductorsprovide an Ethernet bus between the coaxial connector and modules. 4.The data server recited in claim 3 wherein the transmission linemeanders about the backplane.
 5. The data server recited in claim 4wherein the transmission line has an AC impedance of substantially 50ohms and a DC resistance of substantially 1.37 milli-ohms per inch.
 6. Adata server, comprising:a cabinet having a plurality of slots therein; abackplane section disposed at a rear of the slots, such backplanesection having mounted thereto a corresponding plurality of firstmulti-pin electrical connectors; a plurality of hot replaceable, DCpowered, processing unit modules, each one having a printed circuitboard, each printed circuit board having a second multi-pin electricalconnector adapted be plugged into, or un-plugged from a correspondingone of the first multi-pin electrical connectors of the backplane; andwherein such backplane comprises:a printed circuit board having a pairof overlying strip conductors forming a strip transmission line, suchstrip transmission line being configured with electrical characteristicsof a coaxial transmission line.
 7. The data server recited in claim 6wherein the strip transmission line has an AC impedance and DCresistance selected to configure the strip transmission line as anEthernet coaxial transmission line.